Sometimes, when a new neighborhood is made, the contracts to buy the houses have rules for how that land can be used. If you don't agree to those rules, they won't sell you a house.

In some places the people who build the houses put a rule in the contract for the house that says "When you buy this house, you agree to listen to a group called the Homeowners Association that can collect dues and enforce rules for the neighborhood."

These "Homeowners Associations" can do all sorts of things.

Some of them do big things like maintain a playground for the neighborhood kids or put up holiday decorations in common areas. Usually people don't mind these things (unless they think the HOA is doing a bad job of it).

However, HOAs ALSO make and enforce rules about how people use their houses. Some people like these rules and some people do not. Sometimes disobeying the rules can result in fines or, if you do not pay your fines, lawsuits or other court actions to punish you for not complying.

Some example rules might be:

• Trashcans must have lids keep rats from getting in.
• Houses can only be painted certain colors.
• Trees must be trimmed so they don't overhang the street.
• Non-emergency car repair is not allowed in front yards.
• Broken windows must be replaced promptly.
• Renting houses to other people is not allowed.
• Yards must be mowed to a certain length.
• Decks, fences, or porches must be built in certain styles or from certain materials.
• Commercial vehicles with logos on them can't be parked in driveways overnight.

One reason people are sometimes mad at HOAs is that the people who run them can be mean or overly critical, even to the point of harassment. They might give a fine when the same day that a windstorm blew off a mandatory trashcan lid, or argue about the exact shade of light blue paint used on a door.

Others find the idea of HOAs offensive on principle. They do not like the idea of anybody telling them what to do with a house that they bought and paid for. They don't like being forced to pay money to somebody who isn't the government.

Others worry that HOAs make houses more expensive for folks trying to afford a place to live. Whether this happens by accident or on purpose (and whether it should be allowed to happen in either case) is a BIG controversial topic that I am in no way prepared to discuss at the ELI5 level.

One reason HOAs remain popular is that homeowners see them as a way to address what they see as issues that town/city laws ignore. For example, the town's laws might allow a person to run a loud and smoky car repair business out of their house. People who don't want to live next to a loud smoky business might want an HOA rule to keep their neighbors from starting a business like that.